So there’s clearly room for more thinking and discussion about the effects of redistricting. Here are 4 things I think are important to discuss or at least mention.

1) To say that something matters less than is often suggested is not to say that it doesn’t matter at all. This should be obvious, but apparently it’s not sometimes. So I am making it clear, in hopes that people will stop arguing with a straw man.

2) A lot depends on the counterfactual. As we’ve discussed before, making a causal claim—“the 2011 redistricting caused the Republicans to retain a majority after the 2012 election they otherwise would have lost”—entails making a claim about what the “otherwise” is. The challenge becomes not only agreeing upon some relevant and realistic counterfactuals, but agreeing upon what would have resulted under those counterfactual scenarios. Which is not easy.

In Eric’s original post, he asked a specific question: what was the effect of the 2010 redistricting? So his counterfactual was to compare the 2012 boundaries to the previous district boundaries. People fussed about this—see the comments thread—because who’s to say that the previous boundaries were fair? But Eric’s question was about the most recent redistricting, something many people were discussing, so his counterfactual was relevant. His analysis suggests that the 2011 redistricting may have hurt Democrats a bit, but not that much. It explains less about why the Democratic gains in the House were small in 2012 than many commentators seem to think.

But we can also consider the effects of redistricting against other baselines. Nick Goedert’s post does this, by comparing the 2012 outcome to the historical relationship between votes and seats from 1972-2010. He finds that the 2011 redistricting played a larger role.

And there could be other baselines or counterfactuals. Others in that comments thread seemed to want to go back before other GOP gerrymanders, perhaps before 2001. Or what if there were no Republican tide in 2010 and Democrats ended up controlling more state legislatures? Or what about other possible maps? The Daily Kos diarist who told us to “suck it” drew up a set of maps that he argued were fair and non-partisan and would have produced a 22-seat majority for the Democrats. Compared to that, the current set of districts undoubtedly favors Republicans.

At the same time, Jowei Chen and Jonathan Rodden drew thousands of maps using similar criteria for fairness and still came up with a pro-GOP bias. Across a very wide range of counterfactual scenarios, the geographic concentration of Democrats will produce votes-seats discrepancies without deliberate partisan gerrymandering. Nick’s analysis also shows evidence of this as well.

My synthesis of all of this is that, yes, the state of the districts as of 2012 is tilted in the GOP’s favor relative to a bipartisan baseline, and this may be the outcome of multiple rounds of redistricting (2001 and 2011, plus the in-between redistrictings, e.g., in Texas). But this GOP tilt could not be completely eliminated via redistricting.

3) A lot depends on what standards for drawing congressional districts you value. “Oh no,” you might be thinking. “The GOP tilt absolutely could be eliminated via redistricting. Why not spread out those geographically concentrated Democratic votes?” This is possible, as Michael McDonald noted, although perhaps not everywhere, as Jonathan Rodden noted. You could probably do it while drawing districts that would respect the standards of compactness and contiguity, at least enough that no court would object. But then you’re doing at least some violence to another standard for districts, which is that they should respect naturally occurring boundaries or communities of interest.

David Butler and Bruce Cain’s book, Congressional Redistricting, makes this important point: you can’t have it all. It is very difficult to achieve equal district populations, respect compactness and contiguity, respect communities of interest, avoid diluting minority voting strength, and create perfectly proportional representation or at least minimize seats-votes discrepancies. As Butler and Cain write:

…almost all the generally accepted principles of redistricting can come into conflict with each other.

So claims about partisan bias in the current set of districts, or claims about what would be true under various counterfactuals, also depend on (often unstated) priorities about which standards are most important and what trade-offs we should make.

4) To say that redistricting matters less than many people think is not to say that the current system of redistricting is a good one. This is another assumption people sometimes make in reaction to Monkey Cage posts like the ones I’ve linked to above. But the assumption doesn’t follow. There may be many very good reasons to reform redistricting—such as by putting non-partisan commissions in charge in more states—even if that reformed process doesn’t transform politics. At a minimum, one can still make the argument on purely normative grounds, and I think such arguments matter.

We’ll continue to report on research about this topic. My hope is that with these ideas stated, the resulting conversation will be more productive.